Such is the torrent of content in television that ideas will sometimes bump into each other and, by odd coincidence, the two must-see sitcoms of the moment – Peep Show (Channel 4) and Miranda (BBC2) – opted for the same radical departure from format in adjacent editions.

In the gross-out male show, David Mitchell's Mark and Robert Webb's Jez spent almost the whole episode locked into the flat and stairwell of the girlfriend of Jez's boss. In the gross-out female show, Miranda Hart and Patricia Hodge as her mother passed the entire half-hour in a therapist's office.

The first reason why the one-set episode should currently have particular appeal in British TV is artistic. The writers on these series – Jesse Armstrong & Sam for Peep Show, Hart and others on her show – have such standards of invention that they are bound to chafe at the conventions of the traditional sitcom, in which the living room, kitchen and bathroom of the characters become as familiar to viewers as their own.

So offering the regulars fresh territory provides visual variation, while the decision then to throw away the key messes with our rhythmic expectation to cut to somewhere else every few minutes. These lock-ins also nod to earlier experiments in other franchises, such as the editions of Hancock and One Foot in The Grave in which the protagonists are in solitary confinement. There could be a season at the BFI.

But the single-room sitcom brings another benefit to the medium in a time of budget cutbacks. While it is true that a new location has to be found, the overall production costs of the episode will be lower, while the focus on the central figures cuts the acting bill, although both Peep Show and Miranda found ways of bringing at least one other recurrent figure into the isolation zone.

It's bad luck for them that they ended up doing it at the same time, but good luck for viewers that our sitcoms are kicking against the pressure of repetition.